Motion picture projector



Feb. 12, 1946. R. J. MILLER 2,394,857

MOTION PICTURE PROJECTOR Original Filed Jan. 11, 1939 2 Sheets-Sheet 1 IN V EN TOR.

5 E4 VMO/VD J N/z 1.52

Patented Feb. 12, 1946 MOTION PICTURE PROJECTOR Raymond J. Miller, Detroit, Mich., assignor to American Pattern and Manufacturing 00., Detroit, Mich., a co-partnership Original application January 11, 1939, Serial No. 250,310, now Patent No. 2,312,663, dated March 2, 1943. Divided and this application June 16, 1942, Serial No. 447,252

2 Claims.

film and actuating the shutter of motion picture projectors has been formed of a plurality of separate but interconnected casings enclosing the driving shafts, gears, etc. of the projector. Considerable dilllculty has been experienced in providing as rigid a mounting as is desirable particularly since the film must be moved to align approximately 1440 separate film frames with the aperture per minute and spaced film driving sprockets positioned on opposite side of the intermittently driven member must be operated at approximately 360 R. P. M.

The shutter to interrupt the fiow of projecting light must be actuated to interrupt the light at least once each time a different film frame is aligned with the aperture and preferably twice, to interrupt the projecting light while the film frame is maintained in alignment with the aperture to prevent visible flicker. The inertia built up by movement of the various parts, particularly the intermittent movement, causes rather severe vibrations which necessitate the provision of a relatively heavy projector mechanism. The size of the unit and the cost of manufacturing it are thus undesirably increased. Difficult service problems are encountered in projectors heretofore .used since in order to replace a portion of the film moving or shutter driving mechanism it is necessary to virtually dismantle the entire projector to effect the necessary repairs.

An object of this invention is therefore to provide a, motion picture projector having unitary means for directing the film through the projector and for actuating the shutter.

Another object is to provide a readily removable unitary gear train assembly having all the necessary interconnected gears and shafts required to actuate the film moving and shutter driving mechanisms.

A further object resides in the provision of an integral gear train carrier adapted to be readily mounted in a projector housing and having the necessary interconnected gears and shafts to actuate the film moving and shutter operating mechanisms so proportioned that the inertia and vibration resulting from rotation of the movable elements is minimized.

A further object is to provide a motion picture projector having a housing separated into mechanism and film compartments wherein an integral driving unit may be removably positioned in the mechanism compartment to provide all the necessary mechanism for actuating the movable parts of a projector.

Another object of the invention is to provide a projector having a closed mechanism compartment housing all the movable elements required in the operation of the projector and wherein meansactuated by movement of the interconnected gears and shafts are provided to thoroughly lubricate all the moving parts in the mechanism compartment.

Yet a still further object resides in the provision of a motion picture projector having a onepiece casing divided by an integral wall into spaced film and mechanism compartments and wherein a removable gear train carrier may be detachably connected to the casing and located therein by suitable cooperating locating means interposed between the projector housing and the gear train carrier.

Still another object is to provide a motion picture projector having an integral gear train carrier wherein a minimum of difierent sizes of interchangeable gears are provided to drive the various film moving and shutter operating mechanisms of the projector.

Another object is to provide a motion picture projector having a housing provided with an intermediate wall adapted to receive a unitary gear train carrier housing and an intermittence mechanism housing operably connected through the gears oi. the gear train carrier to intermittently align successively spaced film frames with an aperture in a film compartment positioned on the opposite side of the intermediate wall.

Other objects and advantages of this invention will be apparent from the following detailed description considered in connection with the accompanying drawings, submitted for purposes of illustration only, and not intended to define the scope of the invention, reference being had for that purpose to the subjoined claims.

In the drawings wherein similar reference characters refer to similar parts throughout the several views:

Fig. 1 is a staggered vertical sectional view of a motion picture projector illustrating the pres ent invention taken substantially on the line |l of Fig. 2 looking in the direction of the arrows. I

Fig. 2 is a sectional view taken substantially on the line 2--2 of Fig. 1, looking in the direction of the arrows.

Fig. 3 is a sectional view taken substantially on the line 3-3 of Fig. 1, looking in the direction of the arrows.

Before explaining in detail the present invention it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanyingdrawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraselogy or terminology employed herein is for the purpose of descriptionand not of limitation.

Referring now to the drawings, it will be observed that a motion picture projector having a main housing I is provided with an intermediate wall 12. The wall I2 is preferably formed integrally with the housing I0 to separate the space within the housing into mechanism and film compartments I4 and IE respectively. The mechanism compartment may be closed by a plate I8 suitably fastened thereto in such a manner as to provide a substantially fiuid tight joint, and the film compartment I6 may be closed by a hinged access door 20 to permit the operator access to the film moving mechanism positioned in the film compartment.

Film 22 may be withdrawn from an upper magazine mounted on the top of the housing III and spaced therefrom by a film magazine adapter 24 and directed into the film compartment I6 by an upper driving sprocket 26. The film passes from the driving sprocket 26 between suitable film' guiding mechanism, and successively spaced film frames are aligned with an aperture 30 in an aperture plate by an intermittently driven sprocket 28.

After passing beyond the intermittently driven sprocket 28 the film is directed over a lower drive sprocket 32 and is directed through an aperture 34 in the bottom of the film compartment I6 pref erably to a sound head positioned to receive film from the projector.

The upper and lower film driving sprockets 26 and 32 are preferably driven at a constant rate of 360 R. P. M. and the intermittently driven sprocket 28 is preferably intermittently driven to align 1440 successively spaced film frames per minute with the aperture 30. This rapid intermittent starting and stopping of the sprocket 28 and its associated driving means builds up considerable inertia which causes undesirable vibration and subjects the driving mechanism to rather severe loads. A shutter is provided to interrupt the flow of projecting light each time the intermittently driven sprocket 28 is actuated. The shutter is preferably provided with an anti-flicker blade to interrupt the projecting light while a film frame is aligned with the aperture 30 to prevent visible flicker.

The upper and lower film driving sprockets 25 and 32 and the intermittently driven sprocket 28 and the shutter driving mechanism are preferably actuated-by a unitary driving mechanism positioned in the mechanism compartment I4. A gear train carrier 40 having upper and lower shaft receiving portions 42 and 44 interconnected by a vertical shaft receiving portion 46 is also provided with an angularly related laterally extending shaft receiving portion 48. The shaft receiving portions 42, 44, 48 and 48 may preferably be formed as an integral casting to provide a more rigid structure capable of damping vibrations and oscillations and to provide a more rigid driving mechanism.

Locating means may be provided between the ear train carrier 40 and the projector housing Ill. One desirable form of such locating means comprises dowel pins 50 preferably carried by the intermediate wall I2 and adapted to project into apertures formed in bosses 52 carried by the upper and lower portions 42 and 44 of the carrier 40. The gear train carrier 40 may be suitably fastened to the housing In as by screw threaded members 54 extending through the intermediate walls I2 and projecting into the upper and lower shaft receiving portions 42 and 44.

A main driving shaft Gll is journalled in the vertically extending shaft receiving portion 46 and is provided with a gear 62 meshing with a gear 64 fixed to a shaft 66 journalled in the vertical shaft receiving portion 46 on bearings 68 and Hi. It will be noted that a flange 12 formed in the shaft receiving portion 48 is provided to form a seat for the bearing 68 and that the shaft 66 is provided with a sleeve I4 interposed between the bearing 68 and the gear to position the shaft 66 in a predetermined vertical position in one direction within the vertical column 48. A sleeve 19 interposed between the bearing 10 and the gear I8 may be provided to maintain the shaft 66 in a predetermined position within the column 46 in the other direction.

The shaft 64 is provided with upper and lower driving gears 14 and I4 meshing with gears 42 and 84. The gears 82 and 44 are fixed to shafts 8i and 48 respectively journalled in the upper and lower shaft receiving portions 42 and 44 respectively. The shafts 44 and 44 project through oil seals positioned in the intermediate wall I2 and drive the upper and lower film driving sprockets 26 and 32 respectively.

The vertical shaft 44 is provided with a gear 94 meshing with a gear 94 fixed to a shaft 98 journalled in the angularly related shaft receiving portion 48 of the gear train carrier 40. The shaft 98 is journalled in bearings I" and I42 respectively positioned in the portion 4!. The shaft 34 is provided with a gear I l I meshing with a gear H2 fixed to a shaft H4. The shaft H4 is operably connected to drive the intermittently driven sprocket 28 through an intermittence movement I24 Journalled in the intermediate wall I2. The structure of the intermittence movement I28 is more clearly disclosed in my co-pending application Serial No. 447,344, filed June 17, 1942.

It will be noted that the gears 14, III, '2, I4, 94 and III! are of the same diameter and are therefore interchangeable. A minimum number of sizes of gears are thus employed to provide the principal drive of the projector.

The shutter driven by the shutter driving shaft I32 is for the purpose of interrupting the flow of projecting light through the aperture 30 at the time the intermittently driven sprocket 28 is moved to align the next successive film frame with the aperture 30 to prevent streaking. Shutters are normally provided with an auxiliary blade to interrupt the projecting light while a film frame is held in alignment with the aperture to prevent visible flicker or a single blade shutter may be driven at double speed to effect the same result.

Since a definite relation must be maintained between the operation of the intermittently driven sprocket 28 and the shutter driving means in order to prevent streaking and visible flicker, some whereupon a fire shutter is lowered across they form of motion compensating or framing means must be provided to maintain the shutter driving mechanism in synchronism with the'intermittently driven sprocket.

The shaft 88 is provided with a squared portion I88 operably connected to a shutter driving shaft I82 through an axially movable gear I84 meshing with and driving the shutter operating gear fixed to the shaft I82. The gear I34 is journalled in suitable bearings. I88 and I38 to facilitate movement along the squared portion I30 of the shaft 88 and is axially extended as illustrated to actuate the shutter driving sprocket I82 as the framing shaft I48 is rotated to vary the position of a film frame relative to the aperture 80. The framing shaft I40 may be operably connected to rotate the intermittence movement I20 to move the dim relative to the aperture for framing purposes as more clearly disclosed in my co-pending application Serial No. 250,310, filed January 11, 1939, now Patent Number 2,312,663, issued March 2, 1943.

The shaft 88 may be maintained in predetermined alignment within the housing portion 48 of the carrier 40 by means of a stop member in the form of an alignment shoulder I80 formed in the portion 48 to engage the inner edge of the outer periphery of the bearing I00. The shaft 98 is preferably provided with a sleeve I82 to engage the inner portion of the bearing I to main-' tain the shaft 88 in a desired lateral position with reference to the other operating portions of the mechanism.

In view of the fact that the mechanism compartment. I4 is a substantially sealed chamber, oil may be distributed therein to lubricate the gears, bearings, shafts, etc. required to drive the film moving and shutter operating -mechanisms. Lubricating oil may be introduced through a filler plug I80 having a suitable filter I82 positioned adjacent the top of the projector housing I0. A sighting glass I84 may be positioned in the intermediate wall I2 adjacent the bottom of the mechanism compartment I 4 whereby the operator may observe the levelof the oil in the -mechanism compartment and observe the circulation of the oil to determine that the pump is operating.

An oil pump I10 may be driven by the main driving shaft 80. Any suitable form of oil pump may be employed such for example as a gear pump illustrated in Fig. 3 having a casing I12 receiving matching gears I14 and I18 to withdraw oil from an inlet port I18 adjacent the bottom of the mechanism compartment I4 and direct it through a conduit I80 communicating by way of a check valve I84 with conduits I88 and I88. The

conduit I88 communicates with several ducts directed to deliver oil wherever needed to lubricate the moving parts of the projector such as to the gears 18 and 82 positioned adjacent the top of the mechanism compartment and the conduit I88 is directed to deliver oil to the shutter driving gears. A conduit I80 is provided to supply oil to the intermittence sprocket driving mechanism.

A conduit I92 communicating with one of the conduits I88 or I88 is provided to supply oil under pressure to actuate a pressure operated hydraulic aperture 38 to interrupt the flow of projecting light through the aperture 88.

Since the mechanism compartment I4 is substantially closed, a spray of oil may be provided therein to thoroughly lubricate all of the moving parts.

In operation the drives for the film driving sprockets, intermittently driven sprocket and shutter mechanisms are transmitted through the interconnected' ears mounted in the unitary gear train carrier removably positioned in the mechanism compartment I4 of the motion picture projector. Since the gear train carrier is a unitary structure thecasting ma be positioned in a fixture and machined with greater accuracy than where a plurality of separate and independent ,units must be aligned to provide a carrier for the gears and shafts. Greater accuracy in alignment of shafts and gears is therefore assured and minimum cost in the manufacture may be main tained.

The gear train carrier being a unitary structure having all of the interconnected gears and shafts required to effect the drive of the film moving and shutter operating mechanisms, may be readily removed from the projector housing for service and repair.

To "remove the gear train carrier all that is necessary is that the film driving sprockets 28 and 32 and the fastening means 84 be removed. The intermittence movement I28 being an integral. unit remains in the intermediate wall I2 and the shutter driving shaft I 32 remains journalled in the housing I0 of the projector,

Synchronizing means are' provided to ensure proper alignment of the intermittence sprocket driving mechanism with the shutter operating mechanism when the gear train carrier is reas sembled in the housing In of the projector. Any gear train carrier assembly'can thus be assembled in an housing I0 because the parts are accurately aligned and duplication of the parts is easy in view of the improved design whereby unior replacement of damaged parts is thus mate- I rially reduced and the projector can be returned to service in a minimum time because the damaged or worn parts can be replaced by a repaired or reconditioned unit and the damaged parts may be repaired at leisure. A considerable saving is thus effected for exhibitors because rather than fire shutter aligned with the aperture 30 to maintain the fire shutter in the elevated or operative position when the oil pump I18 is operating to supply a predetermined pressure to the conduits. When the-operation of the pump stops or decreases to a substantially predetermined point the manually controlled settable ball check valve interrupts the flow of oil through the conduit I92 maintaining extra complete projector units it is sufficient to maintain extra unit assemblies which may be readily exchanged for damaged or worn units of a projector in such a manner that the projector ma be returned to service in the minimum time.

This is a division of my co-pending application Serial No. 250,310, filed January 11, 1939, now Patent Number 2,312';663, issued March 2, 1943.

I claim:

1. In a motion picture projector adapted to project successively spaced independent visual images carried by consecutively spaced film frames, a housing including spaced film and mechanism compartments, a pluralit of spaced film driving sprockets in the film compartment and a shutter to momentarily interrupt the projection of said images, the combination or an integral shaft and gear train carrier having vertically and horizontally extending shaft receiving columns in the mechanism compartment, guiding means including cooperating apertured bosses and dowel pins interposed between the carrier and housing to accurately align the carrier with the housing, fastening means to detachably connect the carrier to the housing, and shafts in the carrier operably connected to drive said sprockets and shutter.

2. In a motion picture projector adapted to project successively spaced independent visual images carried by consecutively spaced film irames, a housing, a plurality of spaced iilm driving sprockets in the housing and a shutter to momentarily interrupt the projection of said images, the combination of a gear train carrier having verticall and horizontally extending shaft receiving columns in the housing, guiding means including cooperating apertured bosses and dowel pins interposed between the carrier and housing to accurately align the carrier with the housing, fastening means to detachably connect the carrier to the housing, and gear connected shafts in the carrier to drive said sprockets and shutter.

RAYMOND J. MILLER. 

